Concrete mixers, and particularly those mounted on vehicles, are very important to the construction industry because they are necessary for mixing concrete and for the timely transportation of concrete to construction sites for pouring into forms or cavities. Many concrete mixers discharge the mixed concrete down the discharge path of an articulated chute of two or more sections to or near the specific location desired. Many on-site concrete mixers employ similar articulated chutes or tubes to deliver mixed concrete to a desired specific location.
A necessary part of the concrete delivery and pouring process is the cleaning of the delivery chute to thereby prevent the buildup of hardened concrete in the mixer and on chute discharge path surfaces. In the past, after discharging the load from the mixer, the chute was washed clean with water, and the resulting residue dumped in vacant land or fields. This concrete residue created environmental problems, as it hardened, making the soil unworkable. In addition, the contamination of the soil by the concrete liquids and solids killed plant life, prevented future growth of plants, contaminated water-ways and was a source of injury to humans and animals.
Because of these disadvantages of the concrete pouring process, many jurisdictions now prohibit the washing of concrete residues from concrete chutes. As these disadvantages become more well-known, many cities and towns are expected to have such prohibitions in the near future. As a result of such present laws, chutes are now only scraped after delivery of the concrete, as best as can be accomplished with a scraper, shovel or similar device. The amount of concrete residue remaining in the chute varies greatly, depending upon the consistency of the slurry, the abilities and motivation of the operator, and the time permitted for achieving the cleaning of concrete residues from the chute after delivery.
Such concrete residues can constitute a major safety hazard, because concrete delivery vehicles travel on public roads and highways in order to return to their fixed base or batching plant. During such travel, loose particles, aggregate rocks and clumps of concrete sometimes fall from the chute, which often results in damage such as broken windshields, dents, and damaged paint to other vehicles on the highway. In addition, the unwanted discharge of concrete may also result in injury or death to people struck by such particles, aggregate rocks and clumps. Unwanted discharge may result also in vehicular accidents. As a consequence of these hazards, it is unlawful to drop or discharge anything onto public roads and highways.
U.S. Pat. No. 5,354,128 to Lewis discloses canvas cap, configured to be manually stretched, by the operator of a cement truck, over the end of a folded chute, and fastened thereto by multiple elastic cords. This canvas device of Lewis is not substantial enough to withstand the load and wear and tear that is encountered during the normal operation of a cement truck. Because of these deficiencies, the canvas develops tears and holes through which leak cement or concrete aggregate onto streets, highways, and other locations to thereby create inconvenience and hazards. In addition, these canvas devices are sometimes blown from the vehicles while they are traveling at high speed on the highway. An additional problem with canvas covers is that they necessitate the intervention of cement vehicle drivers in placing and securing the cover to the chute after each operation. As a result, cement truck drivers frequently discard the device, thereby leading to a loss of protection, potential liability from unwanted discharge onto other vehicles and onto the highway, and conflict between drivers and company management. These deficiencies result in the problems and dangers listed above.
U.S. Pat. No. 5,186,299 to Stimson shows another device which attempts to solve the problems common to cement truck chutes but falls far short of doing so. The device of Stimson is a manually installed, rigid closure, which blocks the discharge path from the truck to the end of a cement chute but only at the end of an unfolded chute. Thus, the Stimson device does not seal the opening created by the folded segments of a chute and therefore does not function to prevent the unwanted discharge of concrete when a delivery vehicle to which it is attached is in transit on roads and highways. In addition, the Stimson closure is not permanently attached to the chute. Because of this, use of the device presents the added problem of accidents due to loss of the closure during transit, that is, the possibility of the Stimson device falling off of the truck while it is moving.
Accordingly, there remains an important and urgent need for an apparatus which is rugged, reliable, and favored by the drivers of cement delivery vehicles, which automatically positions itself to cover the opening formed by the ends of the segments of a folded concrete chute to thereby prevent debris from falling from concrete vehicle chutes while the vehicles are on roads and highways, or in environmentally protected or restricted areas.